Chemical Sensitivity

Multiple Chemical Sensitivity

Question: Two years ago there was a chemical spill at my workplace, and many of my co-workers and I became ill immediately after the exposure. Since then, I haven't been the same. It feels like I can't think as clearly now, and I seem to be allergic to almost everything, including perfumes, cosmetics, detergents and household cleaning products. I heard about multiple chemical sensitivity (MCS) on a radio talk show, and I think I am chemically sensitive. When I asked my doctor about MCS, he didn't have much to say about it. What can you tell me about multiple chemical sensitivity?

Answer: I can tell you that multiple chemical sensitivity (MCS) is something of a medical mystery. The medical community is divided over whether or not MCS actually exists.

Some physicians acknowledge MCS as a medical disorder that is triggered by exposures to chemicals in the environment, often beginning with a short term, severe chemical exposure (like a chemical spill) or with a longer term, small exposures (like a poorly ventilated office building). After the initial exposure, low levels of everyday chemicals such as those found in cosmetics, soaps, and newspaper inks can trigger physical reactions in MCS patients. These patients report a range of symptoms that often include headaches, rashes, asthma, depression, muscle and joint aches, fatigue, memory loss, and confusion.

Others in the medical community, however, do not accept MCS as a genuine medical disorder. The Centers for Disease Control, for example, do not recognize MCS as a clinical diagnosis. There is no official medical definition of MCS, partially because symptoms and chemical exposures are often unique and are widely varied between individuals. Some physicians are skeptical of concluding that low concentrations of the same chemicals that are tolerated by everyone else can cause dramatic symptoms in MCS patients. The American Medical Association denies that MCS is a clinical condition because conclusive scientific evidence is lacking.

Question: "What are the health effects of chemical mixtures?"

Answer: The human health impacts of chemical mixtures remain unclear. It is extremely difficult to develop an experiment that provides information on the toxicity of possible combinations. Scientists use three general classes of joint interactions: additivity, synergy and antagonism. There are also three possible results in assessing the risk of chemical mixtures which include: overestimation, correct estimation, and underestimation. New approaches to risk assessment include a ranking scheme using toxic equivalency factors and computer modeling.